Process for making prosthetic articles by electrodeposition of metals



Nov. 30, 1943.

' rnocsss FOR MAKING rnoswrww c. A. J. LANDRY I0 ARTICLES BYELECTRQDEPOSITION OF METALS Filed Oct. 3, 1941 Patented Nov. 30, 1943UNITED STATES.. PATENT OFFICE PROCESS FOR MAKING PROSTHETIC AR- TICLESBY ELECTRODEPOSITION 0F METALS This invention relates to the art ofmakin prosthetic articles such as artificial dentures, and moreparticularly to those made of metal.

Objects of the invention include-the provision of a method for makingmetallic dentures in a simple and effective manner by applying threeseparateelectro-platings such that the'fit of the dentures will be verytight and therefore not liable to slipping or loosening while in themouth; the provision of a novel and practical manner of making denturesby electro-deposition'of metals; and a method of producing strong, rigiddentures of chromium and the like.

Other objects of the invention include the provision of a method ofmaking dentures by electrodeposition of metals and the electro-platingof areas of the dentures which are adapted to fit the natural gum ortooth contour.

Other objects and advantages of the'invention will appear hereinafter.

Reference is to be had to the accompanying drawing, in which Fig. 1illustrates a plaster cast of a portion of a mouth to be fitted with aplate and showing how the initial electro-plating is obtained;

Fig. 2 is a plan view of the cast after the initial plating and readyfor the second plating;

Fig. 3 is a side View of the cast of Fig. 2, with a tape partiallyremoved; and

Fig. 4 shows the plate ready for the final electro-plating.

As is usual in dentistry, an impression Of the part affected is takenand a positive cast is made therefrom. This cast can be for an entireplate, for bridgework, or for crowns. The present invention isillustrated as applied to a plate for the upper teeth, it being assumedthat all the teeth have been removed, so that a cast I following the gumcontour as at 2 is produced.

When the cast is finished, it is substantially covered with graphite, asby hand or in a leading machine, or by lead or other metallic foil. Asseen in Fig. 1 of the drawing, the cast is illustrated as covered withgraphite or lead, and apair of wire leads 3 are soldered lightly to theflat bottom of the cast, as this area provides the greatest fiat,uninterrupted area. The wires are connected with a battery or generator,and the leaded cast is placed in a copper, or other metallic bath, for ashort period of time to deposit a very thin shell of the metal over theentire surface of the cast. Copper is preferable for this step in theprocess as it is relatively inexpensive. The purpose of this step is toapply a base metal electricity'conductor on the cast, where theconductor will provide a uniform and sure acting carrier for thecurrent.

The cast is now removed from the bath'and the wires 3-are stripped fromthe bottom surface, this action also tearing off most of the platedmetal from the areas near the attachment-points for wires 3, as thismetal is very thin, not more than .002 of an inch. However, it will befound that the entire top and sides of the castare uniformly anduninterruptedly plated with the metal, this forming a good contactbasefor the secondplating step.

Referring to Figs. 2 and 3, it will be 'seenthat lead wires 4 are laidalong the sides of the'cast at the areas which are not to be built up asthe prosthetic article. These wires are soldered to the metal and thencovered with the masking tape 5 which is used to mask all areas of thecastnot forming the denture. Wires 4 are'thereby firmly sealed to thebase metal plating. Additional wires 6 are secured to the metal base atthe roof portion 1 of the cast to insure proper plating current, and thecast is now ready for the second plating which forms the main part ofthe final denture and which is the thickest plat- After the electricdeposition of about ten to fifteen thousandths of an inch on the exposedparts of the cast, the denture is formed, and this could be used as thefinished product if the second plating were silver, gold, or some othermetal not objectionable to the mouth. However, it is preferred to carrythe process further to achieve the most nearly perfect fit possible, andthis is done by stripping the leaded layer and the original base metallayer off the shell obtained in the second plating. This stripping isdone by chemical means ordinarily, as by acids, or by any otherconvenient or desired means. This of course leaves the prosthetic shell,plate, or crown by itself in substantially finished condition.

The stripped prosthetic shell is then wired in any convenient manner asgenerally indicated in Fig. 4, and returned to the plating bath for thethird and final deposition of metal on all surfaces thereof, both on thefitted surfaces 8 and the wearing surfaces. This plating should be about.001.004 of an inch and is sufficient to build up the fitted surfacesenough to provide a very tight fit in the mouth, and it will be seenthat the third plating conforms to the cast I and will render the shellthick enough on its fitted surfaces to closely embrace the gums. Thisplating may be done or repeated years after initial formation of thedenture to take care of gum shrinkage, etc., and in the first instancewill replace the stripped graphite or lead and underlying base metalthickness plus adding a small extra thickness for the closer fit abovedescribed.

A variation of the process described is contemplated in the manufactureof chromium plates, bridges, etc. Chromium gives an agreeable taste tothe mouth, but is a difiicult metal of which to form electro-depositedprosthetic articles of the nature herein described.

After the base metal or first plating, the cast is prepared as describedand as shown in Figs. 2 and 3, and is placed in a nickel bath, wherein asolid plating about eight to ten thousandths of an inch is deposited.Then the cast is removed fro the nickel bath and placed without change iin a chromium bath to plate the wearing surfaces, which of course arethe exposed surfaces, with a substantial layer of chromium. The cast isremoved from the chromium bath, stripped of the graphite or lead andunderlying base metal or first plating as before, and the entire shellas in Fig. 4 is given an additional chromium plating corresponding tothe above described third plating.

The nickel-chrome denture is extremely strong, rigid, and long lasting,and is provided with a relatively thick chromium plate on all wearingsurfaces with a thinner chromium plate on the fitted surfaces; thenickel core or center imparts strength to the denture, and the chromiumis more easily deposited on the nickel than on copper. In some cases, itmay be desired to use a Ni-Chrome bath in place of the nickel bath, andthis also is contemplated in the invention.

Having thus described my invention and the advantages thereof, I do notWish to be limited to the details herein disclosed, otherwise than asset forth in the claims, but what I claim is:

1. The process of making prosthetic articles by electro-deposition ofmetals including the steps of providing a cast of the member affected,applying a base layer of electric conducting material throughout saidcast, masking parts of the cast not defining the member to leave exposedthose parts of the cast defining the member, electro-depositing a heavynickel bearing metal layer on said exposed parts, electro-depositing alayer of chromium bearing metal on said nickel bearing metal layer,stripping the base layer from the article, and electro-depositing achromium bearing metal layer throughout the entire surface of thearticle for obtaining a close fit at the areas which have been stripped.

2. The process of making artificial dentures by electro-deposition ofmetals including the steps of providing a cast of the mouth, applying athin layer of electric conducting material to all surfaces of said cast,electro-depositing a thin layer of base metal of low electricresistivity to said first named layer, masking the cast to leave theparts corresponding to the affected parts of the mouth exposed,electro-depositing a heavy layer of a nickel bearing metal on saidexposed parts thus forming both wearing and fitted surfaces of saiddenture, said wearing surfaces being exposed and said fitted surfacesbeing next to the cast, electro-depositing a further layer of adifferent metal on said exposed wearing surfaces, stripping said basemetal layer from the article, and electro-depositing a still furthermetal layer on both wearing and fitted surfaces of the stripped denture,said last named deposit being made thicker than the thickness of saidstripped base metal thus obtaining a close fit at the stripped areas.

CHARLES A. J. LANDRY.

